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Tricks to Testing with Minimal
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This information is supplied as a service guide only and Outboardparts.com is not liable
for any misunderstandings, errors or omissions regarding this information. The information
has been obtained from actual unit analysis, parts manuals, and other
sources. ******** |
All Engines |
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| Intermittent Firing: This problem can be
very hard to isolate. A good inductive tachometer (fluke 88 is recommended) can be used to
compare RPM on all cylinders up through wide open throttle. A big difference on one or two
cylinders indicates a problem. |
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| Two or more cylinders misfiring: It is
recommended that both power packs be replaced, unless the problem is a bad trigger. |
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| Engine continuously blows power packs: When
an engine starts blowing power packs repeatedly, especially on the same cylinders, replace
the ignition coils on those cylinders. The inductive kickback from a bad coil can destroy
the packs, even if the coils check good with all known tests. A stator that test good can
also be sending spike voltages to the packs causing them to fail repeatedly. |
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| Visually check the stator, trigger and flywheel:
Cracks, burned marks and bubbling on the stator or trigger indicate a severe problem. If
the stator shows bubbling around the battery charge windings, more than likely you will
have to replace the rectifier/regulator in addition to the stator. Signs of rubbing on the
flywheel usually indicate a bad upper or lower bearing. Check both the outer trigger
magnets for signs of cracking and to be sure that they are not loose. |
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OMC |
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| Open type timer bases: When all cylinders
fire with the spark plugs out, but one or more cylinders quit when the spark plugs are
reinstalled, regapping the timer base may solve this problem. Please refer to the
troubleshooting guide for OMC power packs and CD's item #8. |
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| Quick Start timer bases: These timer
bases cannot be checked like the other timer bases. Please refer to the troubleshooting
guide for OMC power packs and CD,s item #5. |
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| Engines with SLOW features: If the complaint
is that the engine will not slow down after a few minutes and starts shaking real bad,
(but the engine is NOT overheated) try replacing the temperature switch (the one with the
white/black and tan wires coming out). Check routing of tan wires. Relocate as far from
the spark plug wires as possible. Check blocking diode in engine harness. |
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Mercury 6 Cylinder with ADI ignition |
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| No fire on the 1,3,5 or 2,4,6: Swap red and
red/white wires, also blue with blue/white wires. If the problem moves to the other set of
cylinders, the stator is at fault. Disconnect rectifier and retest. If the engine fires
normally, replace the rectifier. If no change, we recommend replacement of the stator. If
you replace the stator and the problem remains try another flywheel, if possible. |
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| No fire on one cylinder: Since this
condition can be caused by the opposite switch box (pack), disconnect the white/black
jumper between the packs and retest. If the dead cylinder starts firing, replace the pack
that was firing all three cylinders. As a verification, swap the trigger and spark plug
wire to the cylinder closest to the dead cylinder, (i.e., if #1 is dead, swap the brown
trigger wire with the white one). If the problem moves to #3, replace the opposite power
pack (switch box). If #1 is still dead, swap the green and green/white coil wires. If the
problem moves to #3, replace the power pack (switch box). Please remember to put the
trigger wires in the correct order after you finish. |
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| Always check the bias circuit: Disconnect the
jumper between the packs on the white/black posts. Check the resistance from the
white/black posts on each pack to engine ground. Standard packs will read from 13-15,000
ohms. Racing boxes will read approximately 9,600 ohms. MAKE SURE THAT THE BIAS READING IS
THE SAME ON BOTH PACKS!!! If the bias is out of specification on one pack you must replace
both packs to prevent future damage. This circuit effects ignition timing and could cause
a powerhead failure. |
| For more detailed information, please refer to the
troubleshooting guides on the other pages. |
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